We're referring, of course, to Mr. Obama's decision on Friday to direct that young illegal immigrants brought to America as children be allowed to remain and work in the country – a move that is expected to strengthen Obama's already-considerable edge among Hispanic voters.

In 2008, Obama won the Hispanic vote handily, beating Sen. John McCain (who had notably gone against his party's conservative base on immigration reform) by a lopsided 67 to 31 percent. This year, the Hispanic vote may play an even more important role, representing a larger share of the electorate overall and in a number of key swing states, with as many as 2 million more eligible voters. So far, polls indicate that Obama is on track to match or even improve on his 2008 performance. A recent Gallup poll – taken before Friday's executive order – showed Obama leading Mr. Romney among Hispanics by 67 percent to 26 percent.

As conservative George Will put it on ABC's "This Week" Sunday: "[Republicans] spent the primary season competing to see who could build the longest, thickest, tallest, most lethally electrified fence. And Hispanics listening to this detected hostility – they're funny that way. And so Romney has a big hole to dig out of, because if he gets under, say, the 31 percent of Hispanic voters that McCain got, he's going to lose."

Monday morning, the Obama campaign continued rubbing it in by announcing the endorsement of popular TV host Cristina Saralegui, who has been referred to as "the Latin Oprah."

All of which leads us to ask: Has Romney's Hispanic problem become so glaring that he now has no choice but to try to one-up the president with a high-profile move – like putting Sen. Marco Rubio of Florida on the ticket with him?

It just so happens that this is a big week for Senator Rubio, whose autobiography, "An American Son," will be released Tuesday. (Scheduling note: Rubio will be the guest at the Monitor Breakfast on Thursday.) Another biography of Rubio, by Washington Post reporter Manuel Roig-Franzia, will also be released this week.

While experts have pointed out that Rubio, whose parents emigrated from Cuba, may not automatically appeal to all Hispanic voters, polls have shown that his hypothetical presence on the ticket does increase Romney's lead in Florida – a state Romney almost certainly will need to win. Rubio also has strong tea party credentials and a magnetic presence on the stump (something Romney himself lacks).

But most important, he would give Romney an instant voice of authority on Hispanic issues. And the historymaking nature of the pick should not be underestimated in its ability to energize Hispanics.

Tellingly, Romney essentially allowed Rubio to speak for him in reacting to the president's move last week. (The Miami Herald called it "Romney's what-Rubio-says immigration stance.") Rubio spoke first, calling the move "welcome news for many of these kids desperate for an answer" but also "a short-term answer to a long-term problem." Then Romney weighed in, saying, "I happen to agree with Marco Rubio." On CBS's "Face the Nation" Sunday, Romney refused to say whether he would overturn Obama's executive action if elected.